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4.2.5. Magnetic fields in violent star-forming (starburst) galaxies

A few galaxies exhibit violent star-forming activities. M82 is one such well-studied galaxy. Reuter et al. (1994) found that the origin of the galactic magnetic fields in M82 was unlikely to be due to a galactic dynamo, but more likely due to plasma streaming from the galactic center caused by a violent starforming activity. The center of M82 is completely depolarized, as expected from strong differential Faraday rotation within a dense medium. In the galactic halo but close to the minor axis of the galaxy, the magnetic field is poloidal or vertical, as expected for an outflowing plasma perpendicular to the disk of the galaxy. In the halo but away from the minor axis, not far from the galaxy's major axis, the magnetic field is found to be parallel to the disk of the galaxy, similar to what is seen in other nearby disk galaxies.